Inside Photoshop: Using CS2's Smart Sharpen Filter

Amount: A higher value simply increases the contrast between edge pixels, giving the appearance of greater sharpness. Easy to overdo; see column at right for specific suggestions.

Radius: Determines the number of pixels surrounding the pixels right along the edge that will be affected by the sharpening. The greater the radius value, the wider the area that will be subject to an increase in contrast -- and the more obvious the sharpening. Too much and you'll get a visible, and probably unwanted, "halo."

Remove: Gives a choice of three methods to find and minimize blur, thus sharpening the image. They are:

1) Gaussian Blur is the kind of blur the Unsharp Mask filter looks for, and it permits the fastest results. This option basically turns Smart Sharpen into the Unsharp Mask filter, only with a pretty interface, so I don't use it very often.

2) Lens Blur is the best choice, in my opinion, because it makes the software do a better job looking for edges and detail. This in turn produces finer sharpening of detail and reduced sharpening halos, and is especially useful for images that have a shallow depth of field.

3) Motion Blur makes the software look for, and reduce the effect of, blur due to camera or subject movement. If you plan to use the Motion Blur option, measure the angle of blur with the Measure tool, found under the Eyedropper tool. Note the measured value in the Options bar readout before entering the Smart Sharpen interface, and then input it into the Angle control field.

More Accurate: Processes the file twice for better removal of blur and enhanced sharpness. Although this can double processing time, it's worth it, so I always leave this option checked.